downie



(No Model.

J; H. DOWNIE.- DENTAL FURNAGE.-

Patented June 6, 1893.

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UNITED STATES PATENT OFFICE.

JAMES II. DOWNIE, OF DETROITJVIIGHIGAN, ASSIGNOR TO THE DETROIT DENTALMANUFACTURING COMPANY, OF SAME PLACE.

DENTAL FURNACE.

SPECIFICATION forming part of Letters Patent No. 499,015, dated June 6,1893..

Application filed November 14, 1892. Serial No. 451,942. (No model.)

To all whom it may concern.-

Be it known that I, JAMES H. DOWNIE, a citizen of the United States,residing at Detroit, in the county of Wayne and State of Michigan, haveinvented certain new and useful Improvements in Dental Furnaces, ofwhich the following is a specification, reference being had therein tothe accompanying drawings.

The invention consists in the peculiar construction of the furnaceitself,in the peculiar construction of the muffle, in the peculiardevices for securing the muffle in position in the furnace, in thepeculiar construction of the shelf at the mouth of the muflie, and inthe peculiar construction, arrangement and combination of the variousparts.

In the drawings, Figure 1 is a front elevation of myimproved furnace.Fig. 2 is a horizontal section centrally through the muffle. Fig. 3 is avertical, central section on linens 0c in Fig. 2. Fig. at is aperspective View of the muffle detached. Fig. 5 is a detachedperspective view of the muffle clamping ring and shelf.

My furnace consists of the furnace casing composed of the lower sectionA and the upper section B, preferably made in two parts, the lowersection enlarged from the bottom upward to its upper end and the uppersection narrowing from its lower end to its upper end. In the previousstate of the art, if furnaces of this description were to be used, thelining was cast separately and the casing was fitted about it, and bymaking the casing in two sections, divided at the point of greatestwidth and narrowing from that point in a both directions,I am enabled tocast or mold the lining G into each section of the casing therebyinsuring a perfect fit, preventing all necessity of trimming or fittingafterward and cheapening the manufacture.

At the top of the lower casing A is an exterior circular flange Dextending around the furnace, except at the point opposite the muffle.The upper casing is provided with ears E and screws F passing throughthose ears and into the flange D, securing the two sections of thefurnace casing together. At the lower edge of the upper section of thecasing I form preferably a D shaped aperture in which I insert a muffleG which extends across the furnace chamber. This muffle is made of lightmetal, such as platinum, and is provided at its forward edge with aflange H adapted to bear against the outer face of the furnace casing.

Iis a clamping ring, corresponding in shape to the shape of the mouth ofthe muffle and adapted to bear against the flange I-I thereof and clampthe same tightly against the outer face of the casing, clamping screws Jsecuring it in position. This ring is preferably made integral with ashelf K which. extends out from the lower edge of the muffle and forms asupport for the articles which may be placed in the muffle or drawntherefrom. The bottom of thelower section of the casing A is providedwith a central aperture in which the gas pipe L is screwed.

M is a supporting base having a corresponding central aperture to allowthe pipe L to pass therethrough and to which the furnace is secured bymeans of screws N entering the bottom of the furnace casing, as plainlyshown in Fig. 3. Around this base concentric with the casing A andseparated a short distance therefrom, is a raised flange 0, within whichis the lower edge of the conical outer casing 0 preferably of sheetmetal and extending from the base M to the under side of the flange D.This I make of sheet metal and preferably ornamental or highly finishedso as to add to the attractiveness of the furnace, and by forming an airspace P between this casing and the furnace casing the heat of thefurnace will not tarnish or injure the outer casing. To preventpossibility of this I form apertures)? at top and bottom to create acirculation of air through that air chamber.

Q is a dome shaped cap or cover, centrally apertured to embrace thefurnace casing, bearing with its lower edge upon the flange D, formingabove this flange an oven R.

R are suitable apertures or door openings formed in the sides of thiscover through which articles may be placed upon the flange D to beheated or to be cooled to a lower temperature slowly after being drawnfrom the furnace.

' What I claim as my invention is- 1.. In a dental furnace, thecombination 0 the furnace casing made in two oppositely taperingsections, a lining of refractory material molded therein, means forsecuring the sections together, and a muffle in the furnace, immediatelyabove the upper edges of the lower section and extending across the samesubstantially as described.

2. In a dental furnace, the combination of the furnace casing made intwo sections, a lining of refractory material therein, one only of saidsections having a recess formed in its edge and a muffle located in saidrecess at the joint between the two sections, substantially asdescribed.

3. In a dental furnace the combination of a furnace casing, an annularflange about the casing, a cap or cover for said flange forming the ovenR in its sides within, and having door openings in its sidessubstantially as described.

t. In a dental furnace, the combination of the furnace casing, thehorizontal annular flange surrounding the casing, the cap Q supported onthe flange having apertures Rand the muffle opening on a level with saidflange, substantially as described.

5. In a dental furnace, the combination of the furnace casing, a muffle,a marginal flange on the muffle, and a clamping ring secured to thecasing for clamping the flange against the casing around the muffle,substantially as described.

6. In a dental furnace, the combination of the furnace casing, a muffle,a marginal flange on the muffle, a clamping ring secured to the casingfor clamping the flange against the casing around the muffle, and ashelf supported by said ring, substantially as described.

7. In a dental furnace, the combination of the furnace casing, a muffle,a marginal flange on the muffle, a clamping ring secured to the casingfor clamping the flange against the casing around the muffle, and ashelf formed integral with said ring and extending out on the plane ofthe bottom of the muffle,substantially as described.

In testimony whereof I affix mysignature in presence of two witnesses.

JAMES H. DOWNIE.

Witnesses:

M. B. ODooHnRTY, N. L. LINDOP.

